5.1.4 Hormonal communication Flashcards
What is the the difference between endocrine and exocrine?
Exocrine - secretion of chemical outside of blood e.g. digestive enzymes
Endocrine - secretion of chemical inside of blood e.g. hormones
What hormones does the pituitary gland secrete? Give their functions
- Growth hormone: controls growth of bones and muscles
- ADH: increases reabsorption of water in kidneys
- Gonadotrophin’s: control development of ovaries and testes
What hormone does the adrenal gland secrete? Give it’s function
- Adrenaline: increases heart, breathing rate and raises blood sugar level
What hormone does the pineal gland secrete? Give it’s function
- Melatonin: affects reproductive development and daily cycles e.g. sleep cycle
What hormone does the thyroid gland secrete? Give it’s function
- Thyroxine: controls rate of metabolism
What hormone does the thymus secrete? Give it’s function
- Thymosin: promotes production and maturation of white blood cells
What hormones does the pancreas secrete? Give their functions
- Insulin: converts glucose to glycogen in the liver
- Glucagon: converts glycogen to glucose in the liver
What hormones does the ovaries secrete? Give their functions
- Oestrogen: controls ovulation and secondary sexual characteristics
- Progesterone: prepares the uterus lining for receiving an embryo
What hormone does the testes secrete? Give it’s function
- Testosterone: controls sperm production and secondary sexual characteristics
Why can steroid hormones pass through the cell membrane?
They are lipid soluble
How do steroid hormones work?
- Bind to steroid hormone receptors within cytoplasm or nucleus
- Hormone-receptor complex acts as a transcription factor which promotes or inhibits transcription of specific gene
- e.g. oestrogen
Why can non-steroid hormones not pass though cell membrane?
Hydrophilic so will be repelled by fatty acids
How to non-steroid hormones work?
- Bind to specific receptors on cells surface membrane
- Triggers cascade reaction mediated by secondary messengers
- e.g. adrenaline
Differences between hormonal and neuronal communication?
Hormonal
- Slower transmission and response
- Hormones travel to all parts of body
- Widespread response
- Long lasting response
- Effect permanent and irreversible
Neuronal
- Faster transmission and response
- Hormones travel to specific parts of body
- Localised response
- Short-lived response
- Effect temporary and reversible
What is the adrenal cortex?
- Outer region of the gland
- Produces hormones vital to life e.g. cortisol and aldosterone
- Steroid hormones
What is the adrenal medulla?
- Inner region of the gland
- Produces non-essential hormones e.g. adrenaline and noradrenaline
- Non-steroid hormones
What is the function of adrenaline?
- Increases heart rate
- Increases blood glucose concentration levels
What is the function of noradrenaline?
- Works with adrenaline in response to stress
- Increases heart rate
- Widens pupils
- Widens air passages in lungs
- Narrows blood vessels in non-essential organs
What is the function of aldosterone?
Controls blood pressure by maintaining balance between salt and water concentrations
What is the function of androgens?
Male and female sex hormones important in menopause
What is the function of cortisol?
Regulates carbohydrate metabolism, blood pressure and cardiovascular function
How is the pancreas an exocrine gland?
Produces digestive enzymes (trypsin, lipase and amylase) and pancreatic juice which are released via pancreatic duct
How is the pancreas an endocrine gland?
Produces hormones (insulin and glucagon) which are released into blood
Which cells in the Islets of Langerhans produce and secrete glucagon?
α cells
Which cells in the Islets of Langerhans produce and secrete insulin?
β cells
__ cells are larger and more numerous
Alpha
What colour are β cells stained?
Blue
What colour are α cells stained?
Pink
What is the endocrine tissue of the pancreas?
Islets of Langerhans (lighter stained)
What is the exocrine tissue of the pancreas?
Pancreatic acini (darker stained)
What is glycogenolysis?
Breakdown of glycogen into glucose
What is gluconeogenesis?
Production of NEW glucose from non-carbohydrate sources e.g. lipids and amino acids
What is glycogenesis?
Production of glycogen from glucose
What happens when blood glucose concentration is too high?
β cells detect change and secrete insulin
How does insulin lower blood glucose levels?
- Increased cellular respiration
- Increased glycogenesis
- Increased conversion of glucose into fats
- Increased absorption of glucose into cells
What happens when blood glucose concentration is too low?
α cells detect change and secrete glucagon
How does glucagon raise blood glucose levels?
- Increased glycogenolysis
- Increased gluconeogenesis (converting amino acids and glycerol into glucose)
Which cells have insulin receptors?
All cells except RBCs
Which cells have glucagon receptors?
Liver and fat cells
What is the mechanism of insulin secretion?
1) Blood glucose above normal levels
2) Glucose enters via carrier protein (GLUT-2)
3) Respiration using glucose occurs and ATP produced
4) ATP sensitive K+ channel closes
5) Depolarisation occurs
6) Voltage gated Ca2+ channels open
7) Increased Ca2+ causes secretory vesicles to release insulin via exocytosis
8) K+ channel re-opens and cell back to resting state
What is type 1 diabetes?
β cells unable to produce insulin
What is type 2 diabetes?
Cannot effectively use insulin
- β cells do not produce enough insulin
- Body cells do not respond to insulin
What causes type 1 diabetes?
Autoimmune response attacking β cells
What causes type 2 diabetes?
- Excess body weight
- Physical inactivity
- Excess overeating of sugars
What are the symptoms of diabetes?
- Glucose present urine
- Excessive need to urinate
- Excessive thirst
- Weight loss
- Blurred vision
What is the treatment for type 1 diabetes?
Regular injections of insulin
What is the treatment for type 2 diabetes?
- Reducing the intake of carbohydrates and sugars
- Exercise
- Medicine
What are the benefits of using GM bacteria to produce insulin rather than animals?
- Pure form so less risk of allergic reaction
- Produced in higher quantities
- Cheaper
- More ethical
What are the problems with a pancreas transplant?
- Demand outweighs availability
- Long term immunosuppressant drugs required so person susceptible to infection
What is potential future treatment for diabetes and what are the benefits?
Stem cells
- Unlimited source of β cells
- Reduced likliehood of rejections
- Injections of insulin no longer required
